diff --git a/src/eval/array.rs b/src/eval/array.rs
index 45f6fcc7c..4ed172aba 100644
--- a/src/eval/array.rs
+++ b/src/eval/array.rs
@@ -1,7 +1,5 @@
 use std::cmp::Ordering;
-use std::convert::TryFrom;
 use std::fmt::{self, Debug, Formatter, Write};
-use std::iter::FromIterator;
 use std::ops::{Add, AddAssign};
 use std::sync::Arc;
 
diff --git a/src/eval/dict.rs b/src/eval/dict.rs
index 2ce3c3f90..0aa9fd4b8 100644
--- a/src/eval/dict.rs
+++ b/src/eval/dict.rs
@@ -1,6 +1,5 @@
 use std::collections::BTreeMap;
 use std::fmt::{self, Debug, Formatter, Write};
-use std::iter::FromIterator;
 use std::ops::{Add, AddAssign};
 use std::sync::Arc;
 
diff --git a/src/eval/ops.rs b/src/eval/ops.rs
index b5fa9f9a0..acceb6267 100644
--- a/src/eval/ops.rs
+++ b/src/eval/ops.rs
@@ -1,5 +1,4 @@
 use std::cmp::Ordering;
-use std::convert::TryFrom;
 
 use super::{Dynamic, Value};
 use crate::diag::StrResult;
diff --git a/src/export/subset.rs b/src/export/subset.rs
index 68d455020..651ed52bc 100644
--- a/src/export/subset.rs
+++ b/src/export/subset.rs
@@ -2,7 +2,6 @@
 
 use std::borrow::Cow;
 use std::collections::HashSet;
-use std::convert::{TryFrom, TryInto};
 use std::iter;
 use std::ops::Range;
 
diff --git a/src/frame.rs b/src/frame.rs
index f228fe563..7cc564ccf 100644
--- a/src/frame.rs
+++ b/src/frame.rs
@@ -127,18 +127,17 @@ impl Frame {
 
 impl Debug for Frame {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        struct Children<'a>(&'a [(Point, Element)]);
-
-        impl Debug for Children<'_> {
-            fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-                f.debug_map().entries(self.0.iter().map(|(k, v)| (k, v))).finish()
-            }
-        }
-
         f.debug_struct("Frame")
             .field("size", &self.size)
             .field("baseline", &self.baseline)
-            .field("children", &Children(&self.elements))
+            .field(
+                "children",
+                &crate::util::debug(|f| {
+                    f.debug_map()
+                        .entries(self.elements.iter().map(|(k, v)| (k, v)))
+                        .finish()
+                }),
+            )
             .finish()
     }
 }
diff --git a/src/library/mod.rs b/src/library/mod.rs
index a86d8bb34..9e3bf18ba 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -60,9 +60,9 @@ macro_rules! prelude {
 
 prelude! {
     pub use std::fmt::{self, Debug, Formatter};
+    pub use std::hash::Hash;
     pub use std::num::NonZeroUsize;
     pub use std::sync::Arc;
-    pub use std::hash::Hash;
 
     pub use typst_macros::class;
 
diff --git a/src/library/text.rs b/src/library/text.rs
index 05b213c84..4aa1bdec1 100644
--- a/src/library/text.rs
+++ b/src/library/text.rs
@@ -1,7 +1,6 @@
 //! Text shaping and styling.
 
 use std::borrow::Cow;
-use std::convert::TryInto;
 use std::fmt::{self, Debug, Formatter};
 use std::ops::{BitXor, Range};
 
diff --git a/src/library/utility.rs b/src/library/utility.rs
index 5b9831c52..ca9d43508 100644
--- a/src/library/utility.rs
+++ b/src/library/utility.rs
@@ -262,10 +262,10 @@ pub fn upper(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
 
 /// Converts an integer into a roman numeral.
 ///
-/// Works for integer between 0 and 3,999,999 inclusive, returns None otherwise.
-/// Adapted from Yann Villessuzanne's roman.rs under the Unlicense, at
-/// https://github.com/linfir/roman.rs/
+/// Works for integer between 0 and 3,999,999.
 pub fn roman(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+    // Adapted from Yann Villessuzanne's roman.rs under the Unlicense, at
+    // https://github.com/linfir/roman.rs/
     static PAIRS: &'static [(&'static str, usize)] = &[
         ("M̅", 1000000),
         ("D̅", 500000),
@@ -292,7 +292,7 @@ pub fn roman(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     let Spanned { mut v, span } = args.expect("non-negative integer")?;
     match v {
         0_usize => return Ok("N".into()),
-        3_999_999 .. => {
+        4_000_000 .. => {
             bail!(
                 span,
                 "cannot convert integers greater than 3,999,999 to roman numerals"
diff --git a/src/util/mod.rs b/src/util/mod.rs
index 2f91100f0..32ec8dc41 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -9,10 +9,30 @@ pub use mac_roman::decode_mac_roman;
 
 use std::cell::RefMut;
 use std::cmp::Ordering;
+use std::fmt::{self, Debug, Formatter};
 use std::ops::Range;
 use std::path::{Component, Path, PathBuf};
 use std::sync::Arc;
 
+/// Turn a closure into a struct implementing [`Debug`].
+pub fn debug<F>(f: F) -> impl Debug
+where
+    F: Fn(&mut Formatter) -> fmt::Result,
+{
+    struct Wrapper<F>(F);
+
+    impl<F> Debug for Wrapper<F>
+    where
+        F: Fn(&mut Formatter) -> fmt::Result,
+    {
+        fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+            self.0(f)
+        }
+    }
+
+    Wrapper(f)
+}
+
 /// Additional methods for strings.
 pub trait StrExt {
     /// The number of code units this string would use if it was encoded in